The present invention relates to saw assemblies for wound products, and more particularly to saw assemblies having mandrels for at least partially supporting the wound products while they are being cut by a log saw.
Rolled products, such as bathroom tissue, paper toweling, wax paper, foil, plastic sheeting, fabric, or other material found in sheet form are typically produced in two ways. The rolled products are produced either with a core at the center of the roll or without a core at the center of the roll. Due to cost and manufacturing limitations associated with the use of a core, it has become advantageous to produce coreless rolled products. However, to allow a coreless product to be used with existing dispensers designed for cored rolled products, it is typically necessary to include a longitudinally extending aperture through the coreless rolled product.
Coreless rolled products are typically produced on winding mandrels to create the central aperture that extends along the longitudinal axis of the rolled product. The winding mandrel forms a relatively long log of rolled product that is later cut into usable lengths or rolls by a saw blade. A disadvantage of coreless rolled products is that the center aperture has the tendency to collapse when the log is being cut into rolls by the saw blade. Even in rolled products having a core, the amount of force exerted upon the rolled product during some cutting operations can cause the core to deform or collapse if not at least partially supported by a mandrel. For example, some rolled products can be easily deformable or can require larger cutting forces capable of bending, deforming, crushing, or otherwise damaging the rolled product if not supported by a mandrel. Additional design limitations arise due to the conventional practice of cutting logs with a saw that must pass through a length equal to the diameter of the log in order to completely cut the log. A blade that must pass this deeply into the log can often generate significant friction, heat, and undesirable forces during cutting operations, and can result in poor cuts and poor product quality.
Different methods have been developed to alleviate this problem in rolled products with or without cores. For example, tightening the wind of the coreless rolled product can increase the stiffness and rigidity of the rolled product, thereby reducing the amount of aperture collapse. Although this solution can reduce collapse, it can also increase the friction between the saw blade and the log, thereby increasing the difficulty of cutting the log into rolls and calling for larger cutting forces.
In combination with or as an alternative to tightening the wind of a rolled product, some saw assemblies include a mandrel that is received within the aperture of the log to maintain the shape of the aperture during the cutting process and to reduce the amount of aperture collapse. Some saw assemblies, such as the one disclosed in U.S. Pat. No. 5,271,137, include a mandrel positioned entirely on one side of the saw blade during cutting operations upon the log. The mandrel includes an end that is positioned adjacent to the saw blade to support the aperture when the saw blade moves through the log to cut a roll from the log. Other saw assemblies, such as the one disclosed in U.S. Pat. No. 5,453,070, include a first mandrel positioned on one side of the saw blade and a second mandrel positioned on the opposite side of the saw blade. Each mandrel includes an end positioned adjacent to the saw blade to support the aperture when the saw blade moves through the log between the ends of the mandrels. Although it is the intention of these saw assemblies to support the aperture close to the saw blade during the cut, these saw assemblies still allow a substantial amount of aperture collapse that can result in a poor quality cut. In addition, the use of two mandrels (and associated elements and equipment) adds significant cost to log cutting machinery.
In light of the above design requirements and limitations, a need exists for a saw assembly that includes a mandrel which provides superior support of the center aperture of a log during the cutting process, reduces the collapse of the aperture during the cutting process, and allows for the rotation of the logs during the cutting process so the saw blade cuts a roll from the log after passing through less than the diameter of the rotating log, thereby lowering the force and friction applied to the log by the saw blade. Each of the preferred embodiments of the present invention achieves one or more of these results.
In some preferred embodiments of the present invention, an apparatus and method are employed for cutting a rotating log into rolls utilized for preventing or reducing the collapse of a longitudinally extending aperture in the log during the cutting process. Some embodiments of the present invention preferably include a mandrel received within the aperture of the log to at least partially support the log and maintain the integrity of the aperture while the log is being cut by a saw blade. The mandrel can include a longitudinal axis, a first portion, and a second portion along the longitudinal axis. The first portion preferably includes a radially outermost surface defining a first radial distance from the longitudinal axis, and the second portion preferably includes a radially outermost surface defining a second radial distance from the longitudinal axis which can be the same or different from the first radial distance.
Preferably, the saw blade is movable toward the longitudinal axis to a cutting position between the first portion and the second portion. At the cutting position, the mandrel preferably has a third distance between the saw blade and the longitudinal axis, the third distance being shorter than at least one of the first and second radial distances to thereby locate the saw beneath the surfaces of the first and second portions. By positioning the saw blade beneath the surfaces of the first and second portions and by rotating the log, the saw blade is capable of cutting a roll from the log after moving partially through the log. Preferably, the outer surfaces of at least one of the first and second portions maintain the shape of the aperture adjacent to the saw blade during the cutting process. More preferably, the outer surfaces of both the first and second portions maintain the shape of the aperture adjacent to the saw blade during the cutting process.
In some preferred embodiments of the invention, the mandrel is rotatable with the log and includes a third portion connecting the first and second portions. Preferably, the third portion includes an radially outermost surface defining the third radial distance from the longitudinal axis. The saw blade is or can preferably be aligned with the third portion and is movable to the cutting position such that the saw blade is positioned beneath the surfaces of the first and second portions and avoids contact with the third portion as the mandrel rotates with the log. The third portion is preferably a recess that extends around a circumference of the mandrel. In some embodiments, the recess non-abruptly transitions into the first and second portions, such as by having sidewalls that join with the surfaces of the first and second portions at a non-orthogonal angle, by a radiused transitional surface between the sidewalls and the surfaces of the first and second portions, and the like. The transition can preferably reform any partial collapse of the aperture as the log and roll move axially to reposition the log for the next cut or to remove the roll or log from the mandrel. Although a mandrel having a recess extending about the circumference of the mandrel can be rotatable with the log as just described, the mandrel can instead be secured against rotation in cases of logs that can be rotated with respect to the mandrel during cutting operations.
In other preferred embodiments of the invention, the mandrel is secured against rotation, includes a third portion connecting the first and second portions and defining a recess that opens toward the saw blade and that only extends partially around a circumference of the mandrel. The recess can be deeper or shallower than the radius of either or both the first and second portions (i.e., deeper or shallower than the length of the first and/or second radial distances). The saw blade is or can preferably be aligned with the third portion and movable to the cutting position so the saw blade is positioned beneath the surfaces of the first and second portions and does not contact the third portion of the non-rotating mandrel. As with mandrels having a recess extending fully around the mandrel as described above, the third portion preferably non-abruptly transitions into the first and second portions. In addition, the recess preferably non-abruptly transitions into an outermost surface of the third portion joining the first and second portions. The transition can preferably reform any partial collapse of the aperture as the log and roll rotate around the third portion of the mandrel.
More preferably, the third portion is secured against rotation in this embodiment while the first portion is rotatable with the log relative to the third portion. For example, the third portion can be located on a shaft while the first portion can be a sleeve rotatably coupled to the shaft. More preferably, the second portion can also be rotatable and can be an additional sleeve rotatably coupled to the shaft on a side of the third portion opposite the first sleeve.
In other preferred embodiments of the invention, the mandrel includes two or more recesses each having a depth at a corresponding radial distance from the longitudinal axis. Preferably, the mandrel is axially movable to align the blade with the different recesses. Alternatively or in addition, the blade (or saw) can be movable to align the different recesses with the blade. The saw blade is preferably moveable toward the longitudinal axis to a cutting position within any of the recesses. Each cutting position defines a radial position which is preferably shorter than at least one of the first and second radial distances. Preferably, by positioning the saw blade beneath the surfaces of the first and/or second portions in one of the aligned positions and by rotating the log, the saw blade is capable of cutting a roll from the log after moving partially through the log. Also preferably, by axially moving the mandrel to align the saw blade in another position, further cuts can be made in the log in a similar manner.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.